Improvement of a heating device for carrying out temperature-dependent tests on electronic components arranged in a socket

ABSTRACT

The present invention concerns a heating assembly ( 10, 15 ) for generating heat in order to carry out temperature-dependent tests on an electronic component ( 3, 200 ) arranged inside a socket ( 2 ), the heating assembly ( 10, 15 ) comprising: A heating device ( 10 ) comprising electrically conductive material in such a manner as to allow the passage of an electrical current to produce heat; According to the invention, the assembly further comprises: A covering ( 15 ) of thermally insulating material suitable for containing said heating device ( 10 ) inside, the covering having at least an opening on one side for allowing the hear diffusion through said opening; Fastening means for fastening said covering ( 15 ) to a support surface ( 5 B), in such a manner that, while used, the heading device ( 10 ), arranged inside said covering ( 15 ) faces said support surface ( 5 B) through said opening.

TECHNICAL FIELD

The present invention concerns the technical field of electroniccomponents in general and in particular the electronic devices, such asthe socket, which are used in order to test other electronic components.

Therefore, the invention refers to an innovative heating assembly whichallows to carry out temperature-dependent tests on electronic componentsarranged in the suitable socket in easy and versatile manner, inparticular for testing BGA components.

BACKGROUND ART

The socket is a known testing device to test other electronic components(the so-called DUT “Device Under Test”). In particular, the “socket” isa sort of cradle which is fixed to a printed circuit board, named withthe acronym P.C.B, that is Printed Circuit Board. Such a cradle of thesocket has electrical contacts communicating with the P.C.B. and it ismade in such a manner as to form a housing in which the electriccomponent to be tested is arranged (a DUT, such as a further printedcircuit board or a processor). The housing is equipped with otherelectric contracts connecting with the component to be tested (DUT) insuch a manner that the signal emitted by the P.C.B. can be transferredto the component to be tested by means of the socket on which thecomponent is arranged. The P.C.B. sends all the electric signalsnecessary for the test and in this manner, the correct operation of theelectronic component occurs, depending on the kind of test to be carriedout.

It is known that many standard tests have to be carried out atpredetermined temperatures, which are well above the room temperature(for example around 130° C.) and such a temperature has to be maintainedfor a predetermined number of hours.

For this purpose, suitable cabinets are known in the state of the art,acting as ovens and then equipped with suitable heating system. Thevarious sockets, on which the components to be tested have to bearranged, are arranged in such cabinets.

It is obvious that such an embodiment is particularly complex andexpensive, as it requires bulky heating structures with expensivemaintenance costs.

In order to overcome such a technical inconvenience, the same applicantfiled a previous European patent application EP3173798 which discloses anew, compact, efficient and cheap heating device. The publicationEP3173798 is to be considered fully incorporated by reference in thepresent description.

Such a publication discloses a heating device in the form of aconductive multi-layer with resistances incised directly on theconductive layers, and through which a heating is obtained for Jouleeffect.

Therefore, the shape of the device is a tablet formed by many layers,suitably applied to the housing of the socket below the component to betested. A voltage is applied and the passage of current in the incisedresistances allows the heat production for Joule effect.

Nevertheless, such an embodiment cannot be applied inside socketsdestined to test BGA components (acronym for Ball Grid Array). In fact,in this case, the structure of the BGA has an array of contacts whichcovers almost its whole surface and the socket is equipped with anumerous succession of metallic needles which form the pins of electriccontact engaged with the array of contacts of the BGA on one side andwith the contacts of the P.C.B. on the opposite side.

In this manner, such a structure of the socket and the BGA component tobe inserted in the socket has no suitable area for applying the heatingdevice described in such a European application directly below thecomponent to be tested inside the socket.

Substantially, the overall structure of the heating device described inthe previous patent application is not specifically suitable for such anapplication and therefore, it cannot be used.

DISCLOSURE OF THE INVENTION

It is therefore the aim of the present invention to furnish a heatingassembly (10, 15) which solves at least in part all the above-mentionedtechnical inconveniences.

In particular, the aim of the present invention is to furnish a heatingassembly (10, 15) which can be applied to any socket, and in particularto those destined to test BGA, in a suitable position to carry out atest at a predetermined temperature.

The aim of the present invention is also to furnish a heating assembly(10, 15) easily, cheaply and functionally allowing to carry outtemperature-dependent tests on any socket and in particular on the BGAdevice as it is inserted in its suitable socket.

Therefore, these and other aims are achieved with the present heatingassembly (10, 15) for generating heat and carrying outtemperature-dependent tests on an electronic component (3, 200) inside asocket (2), according to claim 1.

Such a heating device (10, 15) comprises:

-   -   A heating device (10) comprising an electrically conductive        material (25) in such a manner as to allow the passage of        electrical current to produce heat. Therefore, the heat is        produced by Joule effect.    -   According to the invention, the assembly further comprises:    -   A covering (15) of thermally insulating material, that is        substantially adiabatic, for limiting the heat dispersion and        suitable for containing said heating device (10) inside.        Therefore, the covering contains heat inside but it has at least        an area for the passage which allows the diffusion of heat        outwards the covering, for example by means of a simple opening        through which the heat can flow.    -   Moreover, fastening means are comprised for fastening said        covering (15) to a support surface (5B), in such a manner that,        while used, the heating device (10) arranged inside said        covering (15) faces said support surface (5B) through said        passage area.

In this manner, all the above-mentioned technical inconveniences areeasily solved.

In particular, thanks to the adiabatic covering 15, the heating deviceinside the covering can produce heat which is directed outwardly throughthe passage obtained in the covering itself. Therefore, as the coveringwith the heating device inside is applied to a support surface whichforms the printed circuit board for the tests, the whole assembly,formed by covering and heating device, can be arranged outwards thesocket in a convenient position such that the heat flow hits the socketwith the component 3 to be tested inside it.

In this manner, it is formed an environment with controlled temperaturewith no need to apply the single heating device in the socket butinstead by suitably applying it outside the socket in a convenientposition.

Therefore, the adiabatic container acts not only as support to apply theheating device 10 outside the socket, but, moreover, it forms anadiabatic barrier which limits the heat dispersion, by directing theheat flow towards the socket.

Advantageously, such fastening means are of the removable type in such amanner that said heating assembly (10, 15) can be applied to saidsupport surface (5B) in removable manner.

Advantageously, said passage area can be in the form of at least anopening obtained in the covering.

Advantageously, a layer of thermally conductive material applied to thepassage area of said opening of the covering can be further comprised inorder to facilitate the heat transfer.

More precisely, said layer of thermally conductive material is arrangedon a surface of the heating device (10) in such a manner as to obstructat least in part said opening for the passage of heat such that saidlayer is interposed between the support surface (5B), to which theheating assembly is applied while used, and the surface of the device(10) which faces said area for the passage of heat.

Advantageously, said heating assembly (10) is in form of a multi-layer.

In this manner, the sizes are compact.

Advantageously, the multi-layer comprises one or more layers ofelectrically conductive material and wherein the layer of electricallyconductive material (25) is insulated from a further layer ofelectrically conductive material (25) by means of the interposition of alayer of insulating material (30), at least one or more of said layersof electrically conductive material comprising a resistance (33) for thepassage of current.

Advantageously, said resistance (33) is in the form of an incisionobtained directly on the layer of electrically conductive material (25).

Such an embodiment helps to compact the sizes.

Advantageously, the container (15) is made at least in part of thermallyinsulating materials, such as:

-   -   Plastic;    -   Teflon plastic;    -   PEEK;    -   Aerogel;    -   Silicone foam.

Such materials are not to be considered limiting and other thermallyinsulating materials, also with different insulating degrees, can beequally used without going beyond the scope of the present invention.

Here it is also disclosed a printed circuit board (5) comprising anupper surface (5A) on which a socket (1) is arranged, preferably asocket for testing a component (3) of BGA type, a lower surface (5B) anda plurality of electric contacts for transmitting the electric signal tosaid socket (1).

According to the invention, the printed circuit board (5) comprises aheating assembly (10, 15) as disclosed above, applied in fixed orremovable manner.

Moreover, advantageously, said heating assembly is applied on thesurface (5B), substantially inside the area delimiting the housing ofsaid array of electrical connections, in such a manner as to be in axisbelow the socket.

BRIEF DESCRIPTION OF THE DRAWINGS

Further features and advantages of the present heating assembly (10,15), will become apparent from the following description of preferredembodiments thereof, given only by way of non-limiting, indicative,example, with reference to the accompanying drawings, wherein:

FIG. 1 depicts a socket in which a BGA component 3 to be tested isarranged; the socket is assembled on a printed circuit board P.C.B. 5and, on the opposite side, it is highlighted the heating assembly objectof the invention always applied to the P.C.B. 5;

FIG. 2 is an enlarged detail of FIG. 1 better depicting the heatingassembly object of the invention;

Figures from 3 to 5 depict a constructive detail of the heating devicealready described in the previous European application EP3173798, fullyincorporated by reference here; in particular FIG. 3 depicts themultilayer structure of the heating device 10, FIG. 4 depicts aresistance 33 preferably obtained by means of an incision obtaineddirectly in the conductive material of the heating device 10 and FIG. 5depicts an example of heat diffusion towards a generic component 200 tobe tested;

FIG. 6 is an axonometric view for highlighting the assembly in its wholeincluding the box-shaped covering in which the multilayer device 10 isinserted; the whole, for example thanks to screws, can be fastened asdepicted in FIG. 1 or FIG. 2;

FIG. 7 depicts the heat advancement according to a simulation test whichhighlights the high heat concentration (approximately 145 Celsiusdegrees) obtained in the area of the component to be tested, thanks tothe underlying application of the described assembly.

DESCRIPTION OF SOME PREFERRED EMBODIMENTS

FIG. 1 depicts an overall axonometric view.

In particular, number 5 indicates the printed circuit board P.C.B.,having an upper surface 5A and a lower surface 5B.

The socket is applied on the upper surface 5A, having a structure 2which forms a cradle 2A in which is inserted the component 3 to betested, in particular the component BGA 3 formed, as it is wellinferable from FIG. 2, by an array of contacts 3 b distributed on itssurface.

Such arrays of contacts 3B, as better highlighted in the enlarged viewof FIG. 2, are connected by means of electric contacts in form ofneedles 4 penetrating through the socket to be connected to electriccontacts provided on the underlying P.C.B. 5.

In this manner, according to the known art, it is possible to test thecomponent 3, by sending suitable electric signals of tests which startfrom the P.C.B.

As it is inferable from FIG. 2, a heating device 10 which produces heatfor Joule effect is not directly applicable inside the socket below thecomponent 3, therefore inside the cradle 2A, due to the plurality ofcontacts 3B in the component to be tested.

It could be potentially arranged inside the cradle 2A above thecomponent 3 but this arrangement would be useless as the heat flow wouldgo upwards without hitting the component 3.

Therefore, there is the need to easily apply a heating devicesubstantially as the one disclosed in the reference applicationEP3173798.

For solving the issue, it has been realized an assembly (10, 15) whichcan be applied externally, and in particular below the socket.

This assembly is formed by a container 15 (or also covering) whichcontains the heating device 10 inside.

The container (or covering) is made of thermally insulating material andis configured to be applicable, in removable manner, to the side 5B ofthe P.C.B., therefore on the opposite side with respect to that wherethe socket is fastened.

The container can have a simple box-like shape so as to form a housingin which to arrange the device 10.

As can be inferred from FIG. 2, the container 10 is arrangedsubstantially in axis with respect to the longitudinal axis of thesocket in such a manner that the produced heat fully hits the componentto be tested, thus flowing upwards.

The container 15 is obviously open by a part thereof so that, asdepicted in FIG. 2, while used, the device 10 contacts the surface 5Bradiating heat towards the overlying component 3.

In this manner, the heat produced by the device can freely radiateupwards and therefore towards the overlying socket and towards thecomponent 3 to be tested but the heat is prevented from dispersingdownwards and laterally, thanks to the insulating walls forming thecontainer itself.

Therefore, this system allows an easy application to any printed circuitboard P.C.B. by making the heat flow converging towards the component tobe tested.

The container can be made of various thermally insulating materials.

In a non-limiting way, for example, it is possible to cite materialssuch as plastic, Teflon plastic, PEEK or aerogel which is a silica gelcontaining micro-bubbles of air. Other usable thermally insulatingmaterials can be, for example, silicone foam.

Common materials internally or externally coated with materials withthermally insulating properties can also be used.

Therefore, the box-shaped container is provided with lateral walls 15Land a lower wall 15I and is open on the opposite side to the wall 15I,so that the heating device 10 can contact the wall 5B and radiate heatfrom this opening.

The walls are obviously continuous to avoid the heat dispersion andtherefore do not have significant openings or openings that imply adispersion of heat.

In this manner, the housing formed by these walls does not dissipateheat.

The power supply for the heating device 10 occurs by connecting orwelding the upper surface, that is the P.C.B. 5.

For example, the thermally insulating container can generally bebox-shaped, of rectangular or quadrangular, in such a manner as toretrace the shape of the heating device 10 which is containing.

Obviously, other box-shaped containers, such as cylindrical, can berealized.

Preferably, the container 10 is equipped with some lateral flanges,which extend radially from the lateral walls 15L (see for example FIG.6) and which are intended for the fastening to the surface 5B. Suchflanges, two for example, lean against the surface 5B and they can haveholes which are arranged in axis with the relative holes obtained on theprinted circuit board 5 for inserting some feed screws. In this manner,the application is firm and quick and the whole assembly (10, 15) caneasily be applied and then removed.

Experimental evidence proves that a layer or a sheet of thermallyconductive material can be interposed between the surface 5B and theheating device 10 in such a way that the heating device does not touchsuch a surface 5B directly.

Substantially, a thin layer of thermally conductive material can beinterposed between the surface 5B and the surface of the device 10. Itremarkably favours the heat diffusion upwards, that is towards thedevice to be tested, thus optimizing further the heat flow and thermalconditions for carrying out the test.

For example, a material that can be used for realizing such a thermallyconductive sheet can be a material with the trademark “Berquist Gap Pad5000 s35”, brand name Henkel.

Even if the above-mentioned material proved to be suitable for thepurposes, other thermally conductive material can be used withouthowever moving away from the scope of the present invention.

The heating device 10 contained inside the container 15 is substantiallythose one described in the application EP3173798 and described below forclarity purposes.

Such a heating device is equipped with at least a resistance throughwhich electric current passes, such that it is heated for Joule effectand therefore produces the heat necessary for heating the component tobe tested.

By suitably adjusting the passage of current, the required temperaturecan be easily obtained and controlled.

In more details, as depicted in the section of FIG. 3, such a heatingelement 10 is realized through a plurality of overlapping layers (25,30) (preferably six conductive layers).

Therefore, it is in the form of a multi-layer.

In particular, conductive layers 25 are provided, preferably of metallicmaterial such as copper, interposed to insulating layers 30, preferablypolyamide.

The purpose of the insulating layer is to prevent said conductive layersfrom short-circuiting each other, thus insulating from each other.

Therefore, each layer forms a surface of predetermined thickness andinterposed each other as per section of FIG. 3.

Any shape can be provided, such as square, rectangular or circular metaltablet.

The thicknesses are reduced, approximately a millimeter as a whole.

As highlighted in the section of FIG. 4, a conductive track 33 isobtained in one or more conductive layers, in such a manner as togenerate a resistance for the passage of current.

The resistance is preferably obtained by removing and then carving thelayer according to the required geometry (generally a sort of wavyline).

The first and the last conductive layer are preferably covered orgold-plated for protecting them from corrosion. Preferably, but notnecessarily, the resistance is not obtained on them and their purpose,as they are metallic, is to better give off the heat outwards.

The realization of resistances by means of an incision of a trackdirectly on the surface of the conductive material (therefore, byremoving the material) has the great advantage of making the device morecompact with a particularly simple productive process, contrary to anembodiment where the track is obtained by pouring a conductive materialwhich generates an increase of thickness.

A plurality of micro holes passing through the whole thickness of thedevice 10 are then provided. Such micro-holes are preferably covered bymetal inside and their purpose is to favour the heat diffusion further.In this manner, the heat radiates towards the overlying component to betested in more efficient manner (see for example FIG. 5).

As depicted in FIG. 3, the contacts 31 are comprised, through them sucha device 10 connects to a voltage for generating the passage of heat.Therefore, the contact 31 connects to a complementary contact. Thecontacts are preferably obtained on the first metallic tablet 31 which,as mentioned, can be lacking in the resistance track and it is connectedwith the circuit board 5.

Moreover, in order to pass current through all the layers equipped withtrack, they are connected each other by means of one or more ducts 32,in which an electric cable passes and physically connects all the copperlayers for injecting the voltage of the passage of current.

The advantage of realizing a multi-layer element is that it is possibleto maintain extremely reduced sizes and obtain a high heat at the sametime. In fact, a track for the passage of current can be obtained oneach layer. Therefore, the more layers there are, the greater the heatproduced, thus maintaining at the same time reduced encumbrances (thestructure increases its height but not its width).

Therefore, such a device can be miniaturized at will.

Moreover, the realization of incised tracks further contributes toreduce thicknesses.

Moreover, it is possible to equip one of the conductive layers,preferably one of the two external ones, a contact with an electricwiring connectable to an external control device (for example a PC). Inthis manner, it is easy to monitor the reached temperature and adjustand vary it depending on needs, by increasing or reducing the passage ofcurrent.

Such an assembly (10, 15) can be an independent component, thereforeproduced and sold independently and easily applicable to any printedcircuit board P.C.B. for testing components 3 by means of theabove-mentioned rapid fastening means, such as feed screws or tripsystems.

Alternatively, it can be already in-built in the P.C.B. or in a socketfor carrying out such tests.

While in use, therefore, it is sufficient to apply such a heatingassembly (10, 15) on the lower surface 5B of the circuit board P.C.B. 5,that is below the socket, and inject current to produce heat.

The thermally insulating box will manage the heat diffusion towards thesocket and therefore towards the component 3 to be tested.

The interposition of a thermally conductive layer favours further theheat diffusion towards the component to be tested.

Even if the present invention is preferably intended for testing BGAcomponents, its use as described is not excluded for testing anycomponent 200 arranged inside a socket, even if there is sufficientspace to insert directly in the socket the device 10 below the componentto be tested.

Therefore, its applicability outwards allows the sizes of the heatingdevice 10 not to be necessarily bound to the size 2A of the housing ofthe socket, thus making the system very versatile.

1.-17. (canceled)
 18. A heating assembly (10, 15) for generating heatand carrying out temperature-dependent tests on an electronic component(3, 200) of BGA type when arranged, in use, inside a socket (2)comprising an array of contacts engaging with the array of contacts ofthe BGA component, the heating assembly (10, 15) comprising: a heatingdevice (10) electrically conductive in such a manner as to allow thepassage of electrical current to produce heat; characterized in that theassembly further comprises: a covering (15) of thermally insulatingmaterial (25) for limiting the heat dispersion and suitable forcontaining said heating device (10) inside it, the covering generallybeing box-shaped and comprising lateral walls (15L) and a lower wall(15I) in such a manner as to form a thermally insulated housing for theheating device and having, to the opposite side to said lower wall(15I), at least an opening for allowing the heat diffusion outwards thecovering; fastening means for fastening said covering (15) to a supportsurface (5B) outside the socket, said fastening means being arranged insuch a manner that, while used, the opening faces said support surface(5B) as the covering is fastened to said support surface.
 19. A heatingassembly (10, 15), according to claim 18, wherein said lateral walls(15L) and said lower wall (15I) are substantially lacking in openings.20. A heating device (10, 15), according to claim 18, wherein saidfastening means are of the removable type, in such a manner that saidheating assembly (10, 15) can be applied to said support surface (5B) inremovable manner.
 21. A heating assembly (10, 15), according to claim18, wherein said passage is in form of at least an opening obtained inthe covering.
 22. A heating assembly (10, 15), according to claim 18,wherein a layer of thermally conductive material applied incorrespondence of said opening of the covering is further comprised inorder to facilitate the heat transfer.
 23. A heating assembly (10, 15),according to claim 22, wherein said layer of thermally conductivematerial is arranged on a surface of the heating device (10) in such amanner as to obstruct at least in part said opening for the passage ofheat such that said layer is interposed between the support surface(5B), to which is applied the heating assembly while used, and thesurface of the device (10) which faces said passage of heat.
 24. Aheating assembly (10, 15), according to claim 18, wherein said heatingassembly (10) is in form of a multi-layer.
 25. A heating assembly (10,15), according to claim 24, wherein the multi-layer comprises one ormore layers of electrically conductive material and wherein the layer ofelectrically conductive material (25) is insulated from a further layerof electrically conductive material (25) by means of the interpositionof a layer of insulating material (30), at least one or more of saidlayers of electrically conductive material comprising a resistance (33)for the passage of electrical current.
 26. A heating assembly (10, 15),according to claim 25, wherein said resistance (33) is in form of anincision obtained directly on the layer of electrically conductivematerial (25).
 27. A heating assembly (10, 15), according to claim 18,wherein the covering (15) is made at least in part of thermallyinsulating materials, such as: Plastic; Teflon plastic; PEEK; Aerogel;Silicone foam.
 28. A printed circuit board (5) comprising: an uppersurface (5A) equipped with an array of contacts on which a socket can bearranged and connected for testing a component (3) of BGA type; a lowersurface (5B), characterized in that the printed circuit board (5)comprises a heating assembly (10, 15) according to claim 18, applied infixed or removable manner.
 29. A printed circuit board (5), according toclaim 28, wherein said heating assembly is applied on the surface (5B),substantially inside the area delimiting the housing of said array ofelectrical connections.
 30. A method for carrying outtemperature-dependent tests on an electronic component (3, 200) of BGAtype, equipped with an array of contacts, the method comprising thesteps of: arrangement of the electronic component (3, 200) of BGA typeinside a socket (2) comprising an array of electric contacts engagedwith the array of contacts of the BGA component; arrangement of aheating assembly comprising: an electrically conductive heating device(10), preferably multi-layer, in such a manner as to allow the passageof electrical current to produce heat; a covering (15) of thermallyinsulating material for limiting the heat dispersion, the coveringgenerally being box-shaped and comprising lateral walls (15L) and alower wall (151), said walls being preferably substantially lacking inopenings, in such a manner as to form a thermally insulated housing forthe heating device and having, to the opposite side to said lower wall(151), at least an opening for allowing the heat diffusion outwards thecovering; the heating device being arranged inside said covering (15);fastening of the said assembly, formed by the covering in which the saidheating device is arranged, outside the socket in such a manner that theopening for the passage of heat faces the socket; activation in such amanner that the heating device supplied electrically produces heat thatradiates towards the component to be tested arranged inside the socket.31. A method, according to claim 30, wherein said assembly is appliedbelow the cradle (2A) in which the component to be tested is arranged.32. A method, according to claim 30, wherein the socket is connected toa printed circuit board (5) in such a manner that the array of contactsof the socket is fastened to the array of contacts of the said printedcircuit board (5) and with the assembly which is fastened to the saidprinted circuit board (5) on the side (5B) opposed to that one ofconnection between the socket and the printed circuit board.
 33. Amethod, according to claim 30, wherein the fastening of the heatingassembly occurs by means of fastening screws or removable systems ofvarious types.
 34. A method, according to claim 30, comprising theapplication of a layer of thermally conductive material interposedbetween the surface (5B) and the opening for the passage of heat of saidheating assembly (10).